In modern automotive plants, engine crankshaft and cam shaft journals are cleaned and polished in rather complex machines which rotate filament brushes or other suitable finishing tools against the journal surfaces while also rotating the crankshaft or cam shaft about the axis of the journals. To accomplish this the filament brushes have relatively large internal diameters and are mounted on rings in turn mounted on discs which are in turn mounted in axially spaced fashion along a rotating hollow shaft. The brushes, rings and discs are each welded to each other and the discs welded to the shaft, each disc being between sets of ports in the shafts to permit coolant or lubricant to flow from the shaft generally toward the working face along the outsides of the brushes or tools. The axial spacing of the tools along the shaft permits the throw or offset portions of the crankshaft to move between the brushes or tools as the shaft is rotated.
There may be several such operations employed on the shaft initially utilizing a more abrasive finishing material such as shown and described in prior Warner et al U.S. Pat. No. 4,882,879, and finally a polishing or surface finishing material to obtain the precise required microfinish.
While these machines work very well for their intended purpose, they are difficult, time consuming and costly to change. In order to change such brushes when fully worn, all or most of the welds need to be removed to disassemble the brushes. This is particularly true if the type, size, or spacing of the tools is changed. This requires welds to be broken and residual welds to be ground off to obtain a smooth surface for assembly of new tools. Once the tools, rings and discs are reassembled they have to be rewelded in place. The welding and grinding which must be done in an oily environment may adversely affect the balance of the shaft and machine as well as block flow passages. The operation requires a skilled welder and assistant, and takes approximately four hours. During this period the machine is down as is the process. Because of the difficulty in changing out the finishing tools, there is a tendency to let the tools run beyond their useful lives. This in turn adversely affects the uniformity and quality of finish.